The cyberverse is littered with the carcasses of social media sites that I have used and abandoned. Once I tire of a site, I just don't go back ... except maybe once a year our of curiosity.
MySpace, Bebo, Friendster, ICQ, Twitter, \/\/ave, Foursquare, AIM ... The list goes on and on.
The only reason I'm here on Google+ is because of work. The moment I can, I'll drop it, too.
So, I guess to answer your question, "No, I don't." ;)